Garden Soil pH and Microbes: How Acidity, Bacteria and Fungi Shape a Better Harvest

Most Garden Soil Nematodes Graze Microbes; Only Root-Knot Types Gall Roots Raised Beds and Containers Drift in pH and Need Yearly Retesting Match Lime, Sulfur, Compost or Inoculant to What the Bed's Test Shows Coffee Grounds, Vinegar, Pine Needles and Eggshells Barely Shift Soil pH Bokashi Uses Lactic Acid Bacteria to Pickle Food Waste into Acidic Pre-Compost Ten or More Earthworms per Cubic Foot Signals Biologically Active Garden Soil Soil pH Measured in Calcium Chloride Reads About Half a Unit Below Water pH Holding Potato Soil Near pH 5.2 and Skipping Lime Suppresses Common Scab Raising Soil pH to 6.5–7.0 With Nitrate Nitrogen Suppresses Tomato Fusarium Wilt Spent Mushroom Compost Is Alkaline and Salty, So Keep It Off Blueberries Wood-Chip Mulch Ties Up Nitrogen Only Where Chips Are Dug Into Soil A 24-Hour CO₂ Burst After Rewetting Dry Soil Measures Active Microbes Actinomycete Bacteria Make the Earthy Geosmin Smell and Break Down Tough Residues Trichoderma Seed and Root Treatments Attack Damping-Off and Root-Rot Fungi No-Dig Beds Keep Fungal Hyphae and Soil Aggregates Intact Between Crops Yellow Old Leaves Signal Nitrogen Shortage; Yellow New Leaves Signal pH Lockout Compost Tea Gives Inconsistent Disease Control and Few Nutrients in Garden Trials Aluminum Sulfate Lowers Soil pH Within Weeks but Risks Aluminum Toxicity Denitrifying Bacteria Turn Nitrate into Gas in Waterlogged Garden Beds Phosphate-Solubilizing Bacteria Free Some Bound Soil Phosphorus with Organic Acids Liming Brassica Beds to pH 7.2 Suppresses but Never Cures Clubroot Free-Living Nitrogen-Fixing Bacteria Add Only a Few Kilograms per Hectare Nitrification Slows Sharply Below Soil pH 5.5 and in Cold Soil